1. Field of the Present Invention
The present invention relates to a positioning method and system, and more particularly to a vehicle self-carried positioning method and system, specifically for land and water vehicles, which can obtain highly accurate position measurements of a vehicle on land and in water, exchange the vehicle position information with other users through a wireless communication device, and provide location and surrounding information through a display device by accessing a map database with the position information.
2. Description of Related Arts
Current vehicle navigators depend on the GPS (Global Positioning System). The GPS is a satellite radionavigation system, which is owned, deployed, and operated by the U.S. Department of Defense, but is available for commercial use around the world.
Unfortunately, GPS is vulnerable to jamming and shadowing, especially on land, so that a GPS receiver often can not provide continuous positioning information.
An inertial navigation system (INS) is a self-contained navigation system, which does not need to receive any external radio frequency signals. However, the cost, size, power, and drift of conventional inertial navigation systems prohibit them from use in commercial vehicle navigation applications.
Therefore, it is very desirable to develop a positioning system with reasonable size and weight and power consumption for commercial vehicle operation, which can be used in areas where GPS signals are not available, such as tunnels, forested areas, urbanized terrain, and high Electronic Counter Measure (ECM) environments.
The main objective of the present invention is to provide a vehicle self-carried positioning method and system to determine position information on land and in water with high accuracy such as an accuracy of better than 1 percent of the distance traveled without using GPS or radar updates, wherein output signals of an inertial measurement unit, a velocity producer, and a north finder are processed to obtain highly accurate position measurements of a vehicle on land and in water.
Another objective of the present invention is to provide a vehicle self-carried positioning system which fuses information from the IMU, a velocity producer, and a north finder to achieve a highly accurate self-contained navigation solution with hardware and software modules, including the following capabilities:
(1) Self-contained navigation.
(2) Autonomous position error xe2x89xa61% of the distance traveled without any external RF (radio frequency) signal.
(3) Low cost, low power consumption, lightweight.
(4) A unique sophisticated Kalman filter. It removes the inherent drift of the free inertial positioning solution derived from the output of the low cost coremicro(trademark) IMU by means of fusing information from the coremicro(trademark) IMU, magnetic heading sensor, odometer, and velocimeter.
(5) Smoothing of the output noise of the magnetic sensor, odometer, and velocimeter.
(6) Innovative state variable selection and measurement design of the Kalman Filter, including relative position update, heading update, and zero velocity update.
(7) Autonomous multiple vehicle stop tests and associated zero-velocity updates. The vehicle is not required to perform a zero-velocity update. But, if the vehicle stops at will, the system can exploit such a benefit autonomously.
(8) Advanced IMUxe2x80x94MEMS (microelectromechanical systems) and ASIC (Application Specific Integration Circuit) based coremicro(trademark) IMU: Miniaturized (Length/Width/Height) and Lightweight; High Performance and Low Cost; Low Power Dissipation; Exceptional Improvement In Reliability.
(9) Map database and software module to access surrounding information using the current position solution.
(10) Display device and software module to visualize the location of the user and the surrounding information.
Typical applications of the vehicle self-carried positioning method and system of the present invention include automobiles, railway vehicles, miniature land vehicles, robots, unmanned ground vehicles, military land vehicles, and marine vehicles.
Another objective of the present invention is to provide a vehicle self-carried positioning method and system, which can exchange the vehicle position information with other users through a wireless communication device.
Another objective of the present invention is to provide a vehicle self-carried positioning method and system, which can provide location and surrounding information through a display device by accessing a map database with position information.